textproduct: Rapid City

KEY MESSAGES

- A major warming and drying trend will continue for the rest of this week, with high temperatures reaching the mid-70s to mid-80s by our warmest days Friday and Saturday, and no precipitation.

- Elevated to critical fire weather conditions are expected through Saturday as well, with today and Saturday being the most favorable days to watch. Slightly lighter winds may be a limiting factor for meeting critical fire weather criteria Thursday and Friday.

- A cold front will cross the region by Sunday morning, taking 30 degrees off our temperatures and increasing humidities for a couple days.

DISCUSSION

(This Evening Through Wednesday) Issued at 145 PM MDT Wed Mar 18 2026

Northeastern Wyoming and western South Dakota will remain in northwest flow positioned in between stagnant longwave ridging over the western US and longwave troughing over the eastern US. The western ridge will continue to be our dominant synoptic weather enforcer right through Saturday, supporting a strong warming/drying trend, mostly clear/sunny skies, no precipitation, and periodically breezy conditions. As such, elevated to critical fire weather conditions will be the main weather hazard/impact through the rest of the week. Friday and Saturday continue to look like our warmest days, with high temperatures ranging from the mid-70s to mid-80s outside higher elevations across the Black Hills. These temperatures are 25 to 30 degrees above climatological normals for mid-March. In fact...there is a 60-90 percent chance of temperatures exceeding 80 degrees Saturday afternoon roughly south of a line from Wright, to Rapid City, to Chamberlain, and even a 30% chance of exceeding 85 degrees closer to the Nebraska border! The breeziest days look to be today and Saturday, although not currently reaching advisory criteria. For those planning outdoor recreation, enjoy the taste of summer!

Notable changes remain scheduled for late Saturday night into Sunday morning as a cold front crosses the region bringing an increase in humidity and chopping 30 degrees off our temperatures, with highs only expected to reach the upper-40s to mid-50s Sunday afternoon. 500mb height ensemble cluster analysis continues to show good agreement in the timing and amplitude of this shortwave trough/frontal feature. It's possible some light rain and snow showers will accompany the front (along with a bit of wind), but otherwise dry conditions are expected through the weekend. Some deterministic models suggest a bit of a secondary frontal passage Monday night/Tuesday morning, and while this feature looks quite weak in model wind and height fields aloft with likely no precipitation, it may help sustain those cooler temperatures and slightly moister humidities for a couple days, perhaps offering a brief reprieve on the fire weather side of things.

AVIATION

(For the 00Z TAFS Through 00Z Thursday Evening) Issued At 509 PM MDT Wed Mar 18 2026

VFR conditions are expected through the forecast period.

FIRE WEATHER

Issued At 145 PM MDT Wed Mar 18 2026

High pressure will continue to support a strong warming/drying trend, mostly clear/sunny skies, no precipitation, and periodically breezy conditions right through Saturday, resulting in a multi-day stretch of elevated to critical fire weather conditions across portions of northeastern Wyoming and western South Dakota. No changes have been made today with respect to the ongoing RED FLAG WARNING across some of our southwestern zones. Several surface weather stations have gusted over 25 MPH thus far meeting warning criteria, while RH values have been a bit slow to drop...running generally 20-30 percent so far. Continued drying is expected over the next couple hours though, with the warm temperatures and ongoing drought conditions contributing to the risk as well. Regionwide, critically low RH values are forecast to expand Thursday and Friday, but the flow aloft looks to be slightly weaker and model blends generally support slightly lower diurnal winds with little overlap between critical values of the two elements. Thus, additional RED FLAG WARNINGS are not being issued at this time beyond today. The most near-critical conditions Thursday look to reside over southern Campbell County, as well as across lower elevations just north of the Black Hills into Butte County. We'll continue to monitor trends in model guidance to see if additional warnings will become necessary, especially in these spots. Winds look to increase again across much of the region though Saturday with critical RHs everywhere except perhaps the northwestern South Dakota plains, so this will definitely be a day to watch. Regionwide, expect grassland fire danger to increase throughout the week as well...High to Very High for Thursday across the entire forecast area.

A cold front is forecast to cross the region late Saturday night or Sunday morning, and while no significant precipitation is currently expected beyond a few rain/snow showers, it will bring an increase in RH values and a 30 degree drop in our temperatures. Some deterministic models suggest a bit of a secondary frontal passage Monday night/Tuesday morning, and while this feature looks quite weak in model wind and height fields aloft with likely no precipitation, it may help sustain those cooler temperatures and slightly moister humidities for a couple days before we trend warmer, drier, and breezier again.

UNR WATCHES/WARNINGS/ADVISORIES

SD...Red Flag Warning until 7 PM MDT this evening for SDZ321-322-325- 326. WY...Red Flag Warning until 7 PM MDT this evening for WYZ314-315-317.